We have initiated NMR structural studies on the Bcr Dbl Homology domain. This 23 kD protein domain shows homology to guanine nucleotide exchange factor domains found in Rho family GTPases. These domains activate Rho family GTPases by facilitating GDP dissociation. In vivo, this leads to population of Rho GTPases in their biologically active state where they tranduce signals through multiple signaling pathways leading to diverse biological processes such as changes in cell morphology, cell proliferation and programmed cell death. The functional properties of the Dbl homology domain contained in Bcr have not been well characterized. Therefore, we have initiated NMR structural, biochemical and cell biology studies to better understand the molecular basis of Bcr DH domain function in the cell. We have collected a series of triple resonance data at CMR during a time when our spectrometer at UNC was being upgraded.